This is a replacement i3v X Carriage and fan shroud for the MakerFarm i3v. One is a direct replacement, the no eccentric one removes the x carriage eccentric for a sliding mount instead. The no eccentric mount is superior and is the one I suggest you use. This new carriage supports auto bed leveling, the Hexagon and the Pico hotends (the pico is 20mm longer) has a mount in the back for LED lighting and lots of room for airflow from high CFM cooling fans. The overall design is a single piece and is very stiff but should be printed in PETG or ABS. The 4 large holes can be used for wire management allowing cables to be run directly out of the back of the carriage or the side keeping appearances clean and allowing for additional airflow across the cold end. The Fan shroud is specific to the Pico hotend and uses 4mm magnets to hold the fan to the assembly. The Material Fan can mount between the main fan shroud and your fan to allow air to be directed to both the material being printed and the hotend without requiring a second fan. If you use the material fan you must use a 10+ CFM fan. Keep ahold of the Derlin wheels and axels. You don't need to use magnets to mount the fan, screws will work fine.